If it's just the itching, it can probably wait till Monday given that he's been itchy for about a week. At this point, there's probably nothing they could do for a toxin ingested that long ago (if it turned out that's what the itching was from). So likely all they'd do is supportive therapy for the itching. Of course if things change and he starts developing alarming symptoms like more vomiting, diarrhea, hives, lethargy or goes off his food, an emergency vet visit would be called for. But if he's behaving normally otherwise and seasonal allergies aren't uncommon for him, imo it doesn't sound like an emergency.
If you give him allergy meds (Benadryl, for instance) does it help with the itching?
Not sure why the fingertip would have swelled so, but likely it just reacted to the chemicals in the digestive tract and became porous enough to take on moisture. Good thing he passed it, though! There's always the possibility that there's another stuck in the stomach (we had a dog throw up a piece of dog toy about month after he ingested it
) or passing through the intestine, so watch for signs of tummy irritation (vomiting, esp if it's bloody) and intestinal irritation (diarrhea, esp if it's bloody red or tarry black), or blockage (lack of stool, hunched over in discomfort, no appetite, lethargy, sometimes dry heaving). Any of these symptoms would mean an emergency trip to a vet.
the little devil only ate the one fingertip and will be right as rain now!